GSGS series 4228. First Edition. Italian Istituto Geografico Militare map dated 1929 and photolithographed by the British Ordnance Survey in 1943. The meridians are based on the meridian of Rome, which is 12 degrees, 27 minutes and 7.1 seconds east of Greenwich. The graticule on this sheet West of 6 degrees, 50 minutes East is the French graticule, that to the East of 6 degrees, 50 minutes is the Italian. To convert French geographicals to the Italian system deduct 1.5 seconds from the French latitudes and 8.5 seconds from the French longitudes measured from Greenwich. The 6 degree, 50 minute East meridian drawn in this sheet is on the French graticule. Contours at 20 metres (V.I.). North Italy Grid/French Lambert Grid (Southern).